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There has been much recent interest in long-lived massive particles at the LHC, understood as those with lifetimes between tens of micrometers and several meters. In this context we consider the possibility of long-lived electroweak singlet scalars charged under colour $mathrm{SU}(3)$ with masses near a TeV. The shortest lifetime of interest is already longer than typical hadronisation scales. These exotic new particles would therefore appear as colour singlet bound states of the new scalars with quarks and gluons and it is their colour charge that prevents them from decaying. In particular we consider colour representations consistent with maintaining asymptotic freedom, those with dimensionality $d_R leq 15$. We find that only the octets can decay, and they do so into multi-jet final states through the two-gluon channel. The other representations are stable and form fractionally charged colour singlets, with the decuplet being the only one that can form electrically neutral colour singlets.
We consider a simple extension of the electroweak theory, incorporating one $SU(2)_L$ doublet of colour-octet scalars with Yukawa couplings satisfying the principle of minimal flavour violation. Using the HEPfit package, we perform a global fit to th
We probe small scalar coupling differences via the coherent interactions between two nuclear spin singlet states in organic molecules. We show that the spin-lock induced crossing (SLIC) technique enables the coherent transfer of singlet order between
The coherent high-fidelity generation of nuclear spins in long-lived singlet states which may find application as quantum memory or sensor represents a considerable experimental challenge. Here we propose a dissipative scheme that achieves the prepar
Let $G$ be an edge-coloured graph. The minimum colour degree $delta^c(G)$ of $G$ is the largest integer $k$ such that, for every vertex $v$, there are at least $k$ distinct colours on edges incident to $v$. We say that $G$ is properly coloured if no
Long-lived particles are predicted in extensions of the Standard Model that involve relatively light but very weakly interacting sectors. In this paper we consider the possibility that some of these particles are produced in atmospheric cosmic ray sh